Brake shoe grinder



March 28, 1944. I 4 -Aso 2,345,161

BRAKE snos GRINDER Filec; June 550, 1941 4 Sheets-Sheet 2 v m/IIIIIIIIIIIIIllll m HMWWWwWW I ATTORNEY March 28, 1944. H. THOMASON 21,345,161

BRAKE SHOE GRINDER Filed June so. 1941 4 Sheets-Sheet 5 INVENOR f/ja/mar 760 050/7 BY 4/1: I. ll

ATTORNEY Patented Mar. 28, 1944 UNITED STATES. PATENT OFFICE BRAKE SHOE GRINDER Hjalmar'Th-omason, Los Angeles, Calif.

ApplicationJune 30, 1941, Serial N4). 400,417

7 Glaims.

Thisinvention relates to apparatusfor, grinding or machining arcuate surfaces; more particularly it relates. to amachine for grinding. or machining the wearing surfaces of the brake shoes oiautomotive. vehicles or the like.

In modern automobiles, trucks and such vehicles, eificient braking is highly important, and this: requires among other things, that the-braking surface of thebrakeshoes-have a curvature accurately agreeing with that of the cooperating surface of the brake drum. It is accordingly an object of this invention to provide a machine capable of guiding a brakeshoe witha high degreeof precision.

In such grinders, it has been common to-provide a grinding wheel with a stationary axis,.and to urge the convex sideof the brake-shoe against the wheel. It is an object of this invention: to ensure accuracy in grindingin thisma-nner, by providing a, rigid support for the shoe,- and: an axis about which the shoe support may be oscillated in a direction transverseto-the grinder axis.

It isanotherobjectof this invention to improve such apparatus lay-providing means-wherebythe position of the shoe alongsaid axis may be: a1- tered, makingit'possible to use anydesired'portion of the surface of the grinding roll.

It is still; another: object ofthis invention to make it possible to accommodate a variety of sizesofgshoesin anefiective manner; One dififculty-that oftenarises' is that: a firm grip; upon the-shoe for holdingrit-against thegrinding surface; may cause the-shoe to be sprung-from: its normal unstressed position, and after the grinding operation is performed, andthe grip:relaxed; the-grindingtsuliface departs from: the true cylindricahform desired. It is. another object oi:.this inventiontomake it possible; toclamp the shoe firmly withoutspringing or warping it; and;.capable of; adjustment to take care of. different radii of; curvature of. the shoe;

It. is; still another-object, of this-invention to provide such a clamp which is capableof firmly gripping andsupporting a'brake shoe-eventhough it isdeformedor of irregular. outlineand shape:

Itis astilliurtherobject of this invention-to provide a check gaugeior such apparatus, where= by. the braking: surface -may be checked at any time during the grinding operation, and by which the;shoe.can-bechecked if desired-before the brake lining isapplied.

Itis still another: object? of this; invention. to rov de chz pp ratus1wherein a gaugeyused to determinethe diameter ,ofgthie brake may be used directly to set the machine to grind the required radius of. the arc- This invention possesses many other advantages, and has other objectsiwhich may be made.

. more easily apparent from a. consideration of.

several embodiments. of the invention. For this purpose there are shown afew forms inthe drawings accompanying and forming part of the present specification. 'These forms will now bodescribed in detail, illustrating the general principles ofthe invention; butit is to be understood that this detailed description is not tobe taken in a limiting sense, since the scope of the inven tion is best defined by. the appended claims.

In the drawings:

Figure 1 is a side elevation of the machine;

Fig. 2 isa plan view thereof, partlyin section;

Fig. 3- is an elevation of'the work'carriage, as seen from the left side of Fig. 1;

Fig; 4 is a detail section as seen on plane 4 of Fi 3;

Figs. 5, 6 and 7 are fragmentary sections on an enlarged scale taken along correspondingly numbered planes of Fig; 1; r

Fig. 8 is a transverse section on an enlarged scale; taken along plane 88' of Fig. 2';

Fig. 9 is an elevation partly in section on an enlarged'scal'e, taken along plane 9-9 of 2;

Fig; 10' is a detailsection taken on plane l0-i ii of-Fig; 2;

Fig; 11 is a section on an enlarged scale taken on plane-HH of Fig. 8;

Fig. 12 is a view similar 'to=Fig. 2' but showing a modified form of the invention;

Fig. 13'is' a View similar to Fig; 3, but showing the modifiedform of'work carriage ofFig. 12 in an alternate position;

Figs. 14 and 15 are sections on an enlarged scale taken on correspondingly numbered'planes of Fig. 12';

Fig. 16 is a-detailsection taken on plane l5'|6 ofFig. l3; and

Fig; 1'7is a detail section taken'onplane l1: 1 of Fig. 2.

' Referring'to Figs. 1, 2 and 8" of the drawings, it WibeSeen that themachinecomprises a grinding wheel, such as roll -or cylinder I rotated about an-axisxZ, shown as vertical, and1a-1work supporting. carriage 3 supported so as to' be rotatable about'an axis 4, parallel to axis 2, and spaced therefrom. While anabrasiveiroll-is shown; the term". rotary cutting wheel as" used herein is meanttoapply as well to machining rollers or millers or, cutters, for: example such as Carballoy rollers. Carriage 3 supports asbrake shoe 5 oscillating carriage 3 and shoe 5 about the car- 1 riage axis 4, the surface of shoe 5 is ground or machined to the desired radius, having a center on axis 4. A mechanism 1 is provided for advancing the shoe 5 against the surface of the guiding roll I without altering the position of axis 4. Thus any necessary amount may be removed from the surface of shoe 5, at the same time this surface will always have the desired radius as determined by the relative positions of this axis 4 and the grinding surface of cylinder I. V

The means 8 for positioning the carriage 3 may have suitable indicia 9 (Fig. 1) for indicating the radius to which shoe 5 will be ground. Also the means I may have indicia (Fig. 8) for directly indicating the amount to be ground from the shoe. An arrangement is also provided whereby a pin gauge or inside caliper (Fig. 2) which has been adjusted to the inside diameter of the brake drum with which shoe is to be used may be utilized directlyto position the carriage 3, without the need of transferring measurement accompanied by possibility of errors.

Referring in more detail to the structure, an electric motor |5 (Fig. 1) is mounted on a suitable frame |6 so that its shaft I! (Fig. 2) extends vertically, the axis of shaft coinciding with axis 2. Frame l6 may be conveniently formed of a piece of wrought iron pipe or steel tubing l8 of appropriate size and length having its lower portion divided longitudinally and opened out to form supporting legs, two of which are indicated by numerals I9 and 20 (Fig. l) and which serve to support the structure in a vertical position. The upper end of tube H! has a casting 2| secured thereon in any convenient manner. This casting2| has a lower depending hollow portion, into which the frame of motor is telescoped. Casting 2| is provided with set screws 23 which engage the motor stator, and clamp it firmly in the lower portion of the casting. A socket for the top of pipe I8, offset from axis 2 is also provided in casting 2|. The castingmay be firmly held on the pipe l8 as by clamping screws, not shown.

Motor shaft extends upwardly out of casting 2| and has grinding roll I secured thereon in any appropriate manner. A hood or shroud 24 is mounted on the top plane surface 220 forming a flange on casting 2|. This shroud substantially surrounds roll I, leaving only a portion of its periphery exposed for contact by the surface to be ground (see Fig. 2). Means (not shown) are provided within casting or f ame 2| to create a suction in shroud 24 so that all loose abrasive, dust, etc., incident to the grinding operation are drawn into the shroud 24, and thence delivered downwardly through pipe l8 into a dust bag 25, having a detachable bottom or pan 26 encompassed by the legs IS, 20 of stand I6.

The axes 2 and 4 may be maintained in spaced relation, to determine the radius being ground,

by the aid of a supporting structure that in- I cludes a supporting bar or spindle 30. This bar has an axis transverse to axes 2 and 4 (Figs. 1, 2 and 4), and spaced from them. The bar 30 is slidably supported by a long boss 3| formed on casting 2|, at one side of axis 2. Bar 3|) may be conveniently of circular cross section (Figs. 5, 6 and 7). A key 32 (Fig. 5) fixed in boss 3| engages a. keyway 33 in bar 30 and serving to prevent bar 30 turning about its axis. Bore 34 of boss 3| is intersected by a central, axially extending cut 35, which extends the full length of boss 3 By providing means adapted to close the boss 3| about the bar 30, as for example the cap screw 38 (Fig. 1) and clamping screw 31 (Figs. 1, 2 and 5) adjacent the ends of the boss, bar 36 may be effectively restrained against axial movement. Thus by appropriately tightening one of these screws such as 31, the bar 38 may be clamped in adjusted position. To facilitate such clamping and the freeing of bar 33 for subsequent movement, screw 31 may be provided with a handle 38. Screw 36, after initial adjustment, remains unchanged, and is used only for taking up any looseness between bar 35 and its guide boss 3|.

The outer end of bar 3!) has secured thereon,

a supporting member 4| (see Figs. 1, 2, 3, 8 and 13) Which serves to support carriage 3 for angular .movement about axis 4, as well as adjustment along this axis. For this purpose, bar 30 is positioned in a cylindrical bore in member 4| and is securely fastened thereto as by one or more radial set screws passing through the member 4|. Member 4| may conveniently be a casting having a hub 42 with a bore 43 therethrough whose axis coincides with axis 4, and has a tube 44 slidable therein. Hub 42 has a radial, axially extending slot 45 intersecting bore 43, and is arranged to be clamped about tube 44 to prevent movement thereof by a clamp screw 46. This clamp screw 46 is of novel form and so arranged as. to clamp the hub 42 about tube 44 in response to rotation in one direction, and to positively open the hub 42 upon rotation in the opposite direction. Thus, there is no possibility of the hub 42 freezing about tube 44, and it is always possible to move this tube readily when required. This arrangement will be described in more detail in connection with another part of the apparatus. As shown most clearly in Fig. 8, tube 44 serves to provide a support for mechanism 3 angularly movable about axis 4 of this tube. For this purpose tube 44 is used as a journal bearing. Thus the upper face of tube 44 has a conical seat 48 formed thereon. A corresponding surface 49 of a hub 50 formed on the under side of the carriage supporting or swivel bracket 5| rests therein. Bracket 5| has a depending spindle or shank 52, which has ends closely fitting into the bore of tube 44, but isfreely rotatable therein. A collar 53 is secured on the lower portion of shank 52, as by a set screw 54 and serves to prevent upward movement of shank 52 in tube 44.

The arrangement is such that, due to conical surfaces 48, 49, bracket 5| is confined accurately to rotate about axis 4, such rotation being unrestrained. At the same time, bracket 5| may be adjusted axially of axis 4, by raising and lowering tube 44 in hub 42. The bracket 5| is secured in adjusted position by suitable manipulation of clamp 46.

Bracket 5| has an upstanding rear portion or wall 56 (Figs. 2 and 8) with an opening 51 through which slides a bar 58. The axis of this bar is normal to axis 4, and intersects this axis. Bar 58 may be a round shaft (Fig. 1). A key 59 secured in wall 5'! and engaging a keyway 6|] in bar 58, prevents the bar turning in bracket 5|. The rear portion 55 of bracket 5| also has an axially extending split 62, and a clamp screw 63 is provided to tighten bore 51 about bar 58 and prevent movement thereof. This clamp screw 63 that use r-eviws ms i ed' w er i rotation in one direction sery es to clamp the ar s em e ar u d h ha t. s. 5 while rotation in the opposite direction serves. to positively spread the member 56 and free the shaft. By operation of. clamp 63, it is possible to adjust the bar 58 in the guide 56 and to hold it in any desired position.

Referring to Fig. 11, wall 56 has a boss or ear 64 above cut 62 with a threaded opening. 65 therein, and has a similar boss 66 below cut 62 with a threaded opening 61 therein. The threads in openings 65, 61. are of opposite hand Thus, the thread, in. opening 6 5, may be right hand, while that in opening 6] is left hand, or vice versa. The manner in which the clamp, 63 is made and assembled Wil'l now be described.

The clamp screw 63 is formed of a rodv 68, havingja short threaded. portion 69. spaced from an unthreaded. end portion I6 of reduced diameter. Threaded portion 69 engages the threads of opening. 65. Thelength of reduced portion I6 is somewhat more than the thickness of car 66 plus the width of slot 62. The rod. 68 is. threaded into bore 65 until the lowerend of. the rod is adjacent the lower end of bore 61.. A sleeve H with a smooth bore and an external. thread that. is. of the opposite hand as'compared. with the. threads on portion 69 is' then threaded into bore 61 and over reducedportion 76, until the upperv end of the sleeve is a shortdistance below slot 62. Sleeve II is'then secured to portion I6 as byarcwelding. The upper portion of rod 66 isthen bent over. to form a radially extending handle I2. Rotation of. clamp screw 63 will positively urge bosses 64 and 66 in opposite directions','either together or apart depending on the direction of suchjrotation. The clamp screw 63 cannot be removed-aftertassembly except by 'severing'the portions 69 and ID- II- as by a saw inserted in slot 62-, or by removing sleeve 'II from'portio'n I61 The'ri'ght hand end ofbar' 58 carries the brake shoe 'clarnping'means 6, wherebyitis possible, by longitudinal adjustment of bar 58,"to move the shoe 5 toward or from the grinding surface of wheel 'I The clamping means 6 comprises a supporting member 16 (Figs. 1 and'2) having a central hollow 'hub I5 thatpermit s'the'. means 6-to slide upon bar '58. A pair of spaced'parallel ar'ms I6, ll extend from one endof the hub'tra'nsversely of Jthe bar and respectively above and below its center (see Figs. 1, 2 and 9 The ends of these bars are provided with similar convexly curved surfaces in a horizontal plane, asmarcated at I8, I9.

Member I4 is axially adjustable of bar 58. A screw 8i (Figs. 1, 2fand.8.)secures the member I4 in adjusted position. Bar 58 has a flattened portion 82. (Fig. 8), 'which cooperates. with screw 8| to angularly position the member." on the bar A type of automobile brakeshoein common use has. a generally Teshapedsection; such a shoe'is shown at 96in Figs, 2, 8, 9 and 10. The leg 9-Iof the section is intended to be accommodated betweenflegs'lfi and 11. of the clamp, bei'ng. supported approximately midway. between. them on pinsj62, nearthe ends ofthefllower. arm 11. The inner curved surface 93.0f. shoe'96 restsagainst arcuate surfaces I8, I9 (Fig. 1). Brake shoe. 66 is shown as. having brake lining. 94. on its outer surface, and it. is.this lining that it is desired to grind. a

Such brake. shoes areoften of relatively light material'and it isimportant that the. clamping arms 66 with pins 91 in their extremities.

rra ment. be $1 9 t no de e tm 9 spr n then F t er itiis" i p r ant that t shoe b adequately s p r ed. s th th t me in e is he. gr nd n on a on i n eform Or x the. hoe- A cla p filh se're i n s willbe esc e As a means ofi retaining shoe 9.6 on, supporting member I 4 -,'a frog (Figs. 1, 2 8, 9, and i0.) is mounted thereon having oppositely extending These pins 91. pass through clearance holes 98 in arm I5 and are alined with pins 92. By exerting downward pressure on frog 95, relative to member IA, leg or web 91 of shoe. 96' is clamped between pins 9]; and 92.

Hub 5. mounted on the right hand edge of bar. 58,, as a series of; three. bosses on its upper surface, the center, one of; which, indicated by I66 (Fig. 8 is tapped for. set screw 8| which passes upwardlyv through clearance hole 83 in frog 95, provided with a handle.84 for convenient manipulation. The forward boss I6I is tapped to receive a special stud I62 which passes upwardly through av clearance hole I 63, in frog 65 1 and carries. a sleeve nut I64, at its upper end.

Sleeye nut I64 has. a handle I65 for convenient manipulation, the arrangement, being such. that when nut I64 is screwed. downwardly frog is forced downwardlyv and pins 91 are. clamped against web 91, and toward pins 92. A light compression spring I66 is confinedv about stud. I62 between frog 95 and boss I6I, to. raise the frog as soon as the pressure of nut I64 is released, facilitating removal of=shoe 96.

Erog 95, is arranged so. that pressure exerted by nuti I64. causesthefrog toswing downwardly about a fulcrum. I66, whereby the force is transferred. from. nut I64 to pins 91-. To ensure that these pins 61 are moved in a substantially vertical directionwhen they are exerting aclamping force on web BI, regardless. of the thickness of web 6|, fulcrum I68 is made adjustable in height. Thus, it, may comprise a screw. I 69-, threaded. in a rearwardlyextending arm I I6 on frog 95.. The

. point of this screwis adapted to rest on pad or boss II I on hubI5. By adjusting screw I69 in the arm [ID the effective height of fulcrum I68 is altered.

Since, the arcuate; concave surfaces of the shoe are contacted effectively by the surfaces 18, 19, the shoe can resist anyreasonable flattening force occasioned by the grinding operation. Also, pins 9:] need not all engage in a common plane, and if flange a: of shoe 96. is warped, these pins can accommodate themselves to that condition. This is due to the factthat frog 95.has.suflicient.clearance with respect. to screw.8.I, and therefore frog 95 -is free to tilt within limits. Furthermore, the lowerv ends. of pins 91 are purposely madeconvex to. restrictthe area of :contact' with flange or rib 9i.

The right. hand-end. of. bar... 58 has a. deep. diametralslot. I I3 foraccommodating web 9|. The face of the. bar 58 has horizontalprojections or pins. H4 abovev andbelowtheslot. Supporting member. M is axially adjusted .onbar .58 until pins II4=contact the inner. surface 93of sh oe 96; the member. I4 then "being secured in this'position by.,means.of-set screw.8I. (see Fig, 2). By this means, shoe 66 is adequately.supportedto. preventany flexing. or temporarydeformation' during grinding} at the same time, no force is exerted ontheshoei by the. clamp to. cause deformation ofthe shoe.

Means I T isused. for advancing bar v 56 with respect to bracket 5I during the grinding operation, so as to cause brake shoe 99 to approach the grinding surface I. This means includes a ring or collar II6 (Figs. 2, 3 and 8) mounted on bar 58 so that the bar may slide through it. This collar is located just behind bracket 5I. Collar II6 has a key II'I (Fig.3) engaging keyway 66 in bar 58 to prevent angular movement of the ring about the bar, and is also split asat H8. A clamp screw II9 substantially identical with clamp screw'63 of bracket 5| serves to clamp or release collar II 6 with respect to bar 58.

Clamp II6 has an upward projection I in which is rotatably mounted rod IZI (Fig. 8). Means are provided to prevent axial movement of rod I 2| through projection I20. Rod I2I has an enlarged threaded end I22 engaging a suitably threaded opening I23 in wall 56 of bracket 5I. The rear end of rod I2I carries a knurled operating knob I24 having an extension I25 carrying the appropriate indicia I6 which cooperates with an index mark I26 (Fig. 2) on projection I20. When it is desired to feed rod 58, clamp 6, etc., toward the grinding roll I, clamp 63 is loosened to free rod 58 from bracket 5I, and clamp H9 is tightened to secure ring H6 on the shaft 56. Rotation of knob I24 in the correct direction will then cause collar II6 to approach bracket 5|, moving shaft 58 through it, the amount of movement being indicated by scale I9. Obviously rotation of knob I24 and shaft IEI in the opposite direction will retract clamp 6 together with the shoe 90 from the grinding roll I.

While the screw I22 serves to feed the shoe toward or from the grinding roll I, this feed occurs while axis 4 is fixed with respect to axis 2. Accordingly the radius of grind as determined by the spacing of axes 2 and 4 may be adjusted only if the position of axis 4 is adjusted. For this purpose the position of the swivel bracket 5I is made adjustable by means best illustrated in Figs. 4 and 6. g

The hub of member 4I fastened to bar 30 rotatably supports a short shaft I36. This shaft I30 has an axis parallel to and below the axis of bar 36. Shaft I30 has an enlarged left hand end I3I serving to form a shoulder and having an operating handle I32 fixed thereon as well as a collar I 33 adjustably secured thereon, as by set screw I35. Scale marks I34 on collar I33 cooperate with a stationary index mark on the hub member 4!.

The right handend of shaft I39 has a tube or sleeve I36 as well as a thrust collar I31 secured thereon as by a pin I38. Tube I36 enters a suitable bore I39 in hub 3I formed integrally with casting 2|. The free end of tube I36 has a portion I46 of reduced internal diameter and provided with screw threads which engage a suitably threaded rod I H (see also Figs. 6 and 7). This rod I4! is mounted coaxially in bore I39 and adjustably held against axial movement therein by having its right hand extremity I42 threadedly engage a portion I43 of bore I39 of reduced diaameter. For ease of adjustment as will be presently set forth, the threads on I42 securing the rod MI in place may be of the opposite hand to the threads engaged by sleeve I36. A set screw I44 serves to secure rod MI in adjusted position (Figs. 1 and 6).

Rotation of sleeve I36 by means of handle I32 on the fixed threaded rod I4I will cause the sleeve to move axially of the rod, and thus member 4I, bar 36 and attached parts will move toward or from the axis 2 of the grinder depending on the direction of the threads on rod MI and the direction of rotation. By providing a fixed threaded rod I4I enclosed by a sleeve I36, the threads are protected from dust and grit, and it is much easier to provide proper lubrication. Further, the outside of the sleeve I36 forms a convenient surface for scale marks 9. These marks cooperate with the face I46 (Figs. 1 and 4) of hub or boss 3| as an index, and together with the indicia I34 on collar I33 serve to accurately position the axis 4 of carriage 3 with respect to axis 2 of the grinding roll I.

The position of carriage 3 with respect to hub 31 and index I46, is made adjustable, in a manner supplemental to rotation of handle I32. During this adjustment, handle I32 need not be rotated; thus the marks of scale 9 may be first angularly adjusted by handle I32 so that they appear on the upper portion of sleeve I36 and hence in a position to be readily observed when in registry with the index. Therefore by aid of this supplemental adjustment, it is possible first to bring the carriage 3' to an approximately correct position by aid of handle I32, the graduations 9 being visible; then a fine setting is accomplished without moving the handle further.

The means whereby this is accomplished will now be described. As previously noted that por tion I42 (Fig. 4) or threaded rod I4! which serves to secure this rod in hub 3| has threads of the opposite hand with respect to the threads engaged by sleeve I36. Rotation of rod MI in its support I43 will not only cause the rod I4I to move relative to the support 3|, but will also cause sleeve I36 to move on the rod I4I. Thus, by placing sleeve I36 with scale 9 in the desired angular position, rotation of rod I4I will serve to move sleeve I36 and connected parts to bring axis 4 into a relationship with thesurface of the grinding roll I as indicated accurately by scale 9. Rotation may be conveniently imparted to rod MI by loosening set screw M4 and applying a screw driver to kerf I45 in the end of the rod. After adjustment, set screw I44 is again tightened to prevent further rotation of rod I4 I.

To cause the scale 9 to be always in the chosen visible angular position when any mark thereon is in registry with the index I44, the spacing of the scale marks 9 should be an even multiple of the pitch of those threads of rod I4I which engage the sleeve I36. Further, it is not necessary that the threads on the supporting end I42 be of the opposite hand to those of the rest of the rod I4! if they are of the same hand but of different pitch, the same result will be achieved.

As a means of checking the surface of the brake lining 94 after grinding, both for alinement and radius, as well as checking shoe 90, before the lining is applied, for warping or distortion, a check gauge mechanism I50 is provided (see Figs. 2, 3, 12 and 13). This mechanism is such that it provides a gauging surface adapted to cooperate with the lining or the shoe when swung sufiiciently away from the grinding wheel I about the axis 4.

A cylindrical guide bar I5I (Figs. 2, 3, l3 and 16) is rotatably mounted in a bore I52 in member 4I having its axis horizontal and perpendicular to axis 4. These two axes intersect. Means are provided to prevent axial movement of bar I5I with respect to member M as well as to limit its angular movement (see Figs. 13 and 16). Bore I52 is intersected by a tapped radial hole I53 in which is mounted a set screw I54 having a plane cylindrical end portion I55. This portion I55 engages a circurnferential groove I56 formed near theend of bar II and by engaging the sides of the groove prevents axial movement of the bar. As clearly shown in Fig. 16, groove I56 is of limited angular extent. The ends of the groove by respectively engaging the end I55 of set screw I54 limit the rotation of bar I5! to approximately 90. A compression spring I51 confined between the end of bar I5I and the bottom of bore I52 frictionally restrains rotation of the bar, and also ensures that one side of groove I56 will be in contact with the cylindrical en'd I55 of screw I53. I

Slidably mounted upon bar is a gauging arm I59 having a bored hub I69 through which bar I5I passes. To prevent arm I59 rotating 011 bar I51, hub I66 is provided with a key I 6| (Fig. 1.3) engaging an axially extending keyway I62. in bar I5I. Hub I60 is split on one side as indicated at I63 in Fig. 3 and is provided with a clamp screw I64 incorporating a right and left hand thread to positively open as Well as close the hub, as previously discussed. Arm I59 has an accurately finished plane surface I65 relatively long and narrow, which is parallel with the plane passing through axes 2 and 4; and normal to the axis of bar I5I. This surface acts as a gauging surface. Arm I59 is so positioned on bar I5I with respect to the limiting slot I 56 that it may be turned with bar I5I to occupy either the horizon? tal position of Figs. 1, 2 and 3 where it is out of the way when not in use, or the vertical position of Figs. 12 and 13 ready for.use.-

It is apparent that scales 9. and I34 may be used to accurately position axis 4 with respect to the grinding roll: L scale 9 being preferably graduated in terms of the diameter of the brake drum, Thus for a givenscale setting, say 14" drum diameter, the axis 4 will be half this amount; or 7" from the grinding surface, and the braking surfacewill be ground to this.radius. Then, a shoe, as 99 placed in the clamp 6 and moved into contact. with the grinding surface by the screw mechanism I2I, I24 will when swung about axis 4, have the surface ofbrake lining 94 ground to theipredetermined radius, or drum diameter.

The movement of shoe 96 towards the grindingroll I by means of screw feed .I2I', 1240bviously has .no effect. whatever on. the. radiusto which the shoe will be ground, since this isfdetermined by the position of axis 4.

,However, .it is .commonto grind shoes t'olfit existing brake. drums, whichinvolves determining the diameter of such drums, It is of great convenience to use the gauge with which :such diameter has been measured to directly position the axis 4 at the proper distance from the grinder I without the necessity of reading any measurements.

In Fig. 2, a gauge for determining the inside diameter of a brake drum is indicated by II. Such a gauge is shown and described in a copending application entitled. Adjustable pin gauge and filed in the name of Hjalmar Thomason on December '27, 1938, under Serial No. 247,774. The gauge I I comprises abody por tion I68 carrying oppositely extensible gauging pins I69 arranged for simultaneous inward or outward movement by rotation of a knurled knob I10. Suitable indicia may be provided for ac'c'u rately indicating the distance between the points of pins I69. However, as previously mentioned, no reading of such indiciais required in the pres"- ent arrangement, the setting of pins I69 being used directly to set the swivel bracket 5I with respect to the grinder I, Thus, the gauge I68 has a boss I1I carrying apin I'IZ haVin'g an axis located at definite relationship w th ra spect to the center of gauge 1 I, and normal "to the axis of the gauging pins I69.

Body 2'I of the grinded has an appropriately positioned hole I13 (Fig. 7) for receiving pin I12. Further, member 4| has a hardened steel button I14 (Figs. 1, 2, and 17) so positioned that its hardened plane fac'e contacts the 'e'nd of gauge pin I69 whenthe gauge II is in a horizontal-position. The relative locations of hole I13, button I14, axes 2 and 4, and the grinding surface of roll I are such that with the face of button 114 contacting the end of pin I69 when gauge .II 'is supported in hole I13, axis 4 will :beproperlypositioned for shoes to be ground to the diameter for which gauge II is set. The interior ,cylin .drical surface of hole I13, and the surface of button I14 thus form cooperating gauging surfaces. .i

To provide forvariations in the diameter of grindingrolls, due to initial variations Ofwear, button I15 is adjustable inmem ber 4 I so that the position of its .face with respect to axis 4.;may be alte d. Th s-la e ,7)., t on 14 threaded shank I15 engaging an appropriately hreade 'a rt J n b ss H1 0 me b r A screw I 18 in aperture I 16 serves to lock :button fias s ov ent. v ga Il m al b u -t p 1. s e? check arm I59, asshowninFig. Member tl carries another button I8I),.simi1ar.to button lift and adjustable in the same. manner. Also oss I60 of arm I59 has an ear I8I (shown dotted behind gauge, II in Fig. 12) with an apfilftuif'e 'for receivin pin I12 of gauge. II. rmawan arm I5 in it ver i on au e. I 1 ma be mounted on hub I66, and arm I59 moved axially of bar I62 until :button I contacts the endfof pin I69. The parts are so proportioned anaerranged that when this is donev and usingthe short end of the gauge II, 'face I65 of 'arm.l59w ill be aft a distance from axis 4 equal to half thediam; eter set onthe gauge, or the radius to which the shoe is to be ground. 3

Although Figs. 12 and13illustrate form of clamp for accommodating awi'd hr shoe, the setting and use of thebheck g st e e a witna na row shoa ,7 the check arm I59 properly p'o'sitio ed th; ca i 3 aybe sw n about axis. i. the face of the supported brakesnoe int positionwith face I65 of arm I59, m1 sible to check the radius as well 'as the al' and other oharacteristicspf thefac'e by setting arm I59 and mountingthe; p 0n the r age e ean ly ng the in g; similarly possible to check the shoe for size, deformation andother defects. 7v ,7 A

The brake shoe 9i) discussed incfonneiction with Figs. 2, 8 and 9 is of the type usually usedjon pleasure cars or light t'rucks. I Heavier ,veh'icle's use a much wider shoe as indicated by I in Figs. 13 and l4. Such a shoe requires adiiier ent type supporting clamp from that disclosed in connection with shoe 96, and such a clamp 'is generally indicated by I86 in Figs. 12 13; 14 and 15.

Clamp I 66 is interchangeable with clamp 6, and is intended to be mounted an bar 58, in a similar manner. Thus, clamp 186 includes a lower plate-like member I 81 (Fig. 15') havinga hub I 88 with a bore for receiving bar 58, a set screw I89 (Figs. 13 and 15) for securing the clamp in adjusted position, the same as supporting member I4 of clamp 6.

Lower member 181 has a forwardly extending shelf I90 with horns or projections I9I. The shelf I90 and these horns have a plane upper surface I92 upon which the lower flange of brake shoe I85 is supported (see Fig. 14). Member I81 has also a pair of rearward extensions I93, disposed respectively on opposite sides of hub I88. Each extension I93 has a pair of threaded bosses I94, I95, carrying respectively upstanding threaded rods I96, I91. slidable over each pair of rods I96, I91 is an upper clamp member I98. Upper clamp members I98 areduplicates except for being right and left hand. Each includes a forward projection or horn 200 having an under surface 20I adapted to engage an upper surface of the top flange of shoe I85.. As a means of supporting the rear end of member I98, a knurled nut 202 is provided on threaded rod I9I. Another knurled nut 203 is provided on threaded rod I96, and is adapted by being screwed downwardly on the rod to swing member I98 downwardly about nut 202 as a fulcrum, urging surface 20I against shoe I85, thus confining the shoe I85 between surfaces I92 and As in the first form of clamp described, the upper clamp members I98 can freely accommodate themselves to the corresponding flange surface, even if the surface be warped.- This is due to the independent operation of the two clamping nuts 203 and the clearances between studs I96 and the apertures through the clamp elements.

In case shoe I85 can not be clamped in the above described manner with sufiicient force to hold the shoe against radial movement while being ground, means are provided to positively support the shoe from the rear of the shoe.

Thus, each of the horns or projections I 9I, 290 carries a supporting screw 206 threadedly supported in a boss 201 on the respective horn. The forward end of each screw 296 is coned as indicated by 208 to provide a point contact with a rear surface 209 of shoe I85. The rear end of each screw 206 has a knurled adjusting knob 2 I accommodated in a suitable opening 2II in the clamping member.

To, prevent undesirable looseness of screws 206, each of hubs 201 has a radial hole 2 I3 (Fig. 15) containing aslidable soft metal plug 2. The outer end of hole 2I3 is threaded for a headless set screw 2I5. By screwing set screw 2I5 inwardly, plug 2M is forced against screw 296 and exerts an adjustable amount of frictional restraint against rotation of the screw 206.

It will be apparent that by appropriate adjustment of screws 296 the outside surface 2I2 of shoe I85 may be correctly located with respect to axis 4 and grinding roll I regardless of irregularities in the rear surface209 of the shoe; further that arms I9I and 290 cooperate with screws'286 to firmly secure shoe I85 in clamp I85; at the same time no force is exerted'on shoe I85 tending to cause distortion.

The grinding operation and use of check arm I59 are the same with clamp I86 and a wide shoe I85, as with clamp 6 and a narrow shoe 90.

An important feature of the machine is the provision for adjustment of the work carriage including the swivel bracket 5!, shoe clamp 6 or I86 together with the supported brake shoe in a vertical direction along axis 4. By this adjustment it is possible to bring the brake shoe into contact with different zones on the grinding roll I, thus rendering the entire surface of the roller useable. This prolongs the usefullife of the roll, and also makes possible the use of a grinding roll having zones of different grinding characteristics. Thus inFig. 8 the grinding roll I is shown as having an upper zone 2 I8 of relatively coarse grit, while the lower zone 2I9 is of fine grit. Of course other forms of machining rolls or discs may be used.

What is claimed is:

1. In a grinding apparatus, a rotary cutting wheel having a fixed axis, said wheel forming a grinding surface, an angularly movable support for an object to be ground by the wheel, means providing an axis of rotation for said support, and spaced from the grindingsurface whereby angular motion of the support causes a cylindrical surface to be ground, about said axis of rotation, a spindle upon which said support is mounted, a common frame for supporting said spindle and the wheel, said frame having a socket for slidably receiving the spindle, said spindle being splined in the socket, and means for adjusting the spindle in relation to the frame, for adjusting the position of the axis of rotation.

2. In a grinding apparatus, a rotary cutting wheel having a fixed axis, said wheel forming a grinding surface, an angularly movable support for an object to be ground by the wheel, means providing an axis of rotation for said support,,

and spaced from thegrinding surface whereby angular motion of the support causes a cylindrical surface to be ground, about said axis of rotation, means for adjusting the position of said axis of rotation, and means forming a gauging surface parallel to said axis of rotation and mounted on the means providing the axis of rotation for said support, said gauging surface having a normal thereto intersecting the said axis of rotation and being spaced angularly about said axis of rotation from the line joining the two axes, comprising an arm, means for angularly and axially adjusting said arm about an axis normal to and intersecting said axis of rotation, and means forming a pair of gauging surfaces respectively in fixed position with respect to the arm and to the support for cooperating with a pin gauge todirectly and accurately position the gauging surface in said arm with respect to the axis of rotation.

3. In a grinding apparatus, a rotary cutting wheel having a fixed axis, said wheel forming a rinding surface, an angularly movable support tion, for movement toward or awayfrom the grinder axis.

4. In a grinding apparatus, a rotary cutting wheel having a fixed axis, said wheel forming a grinding surface, an angularly movable support for an object to be ground by the wheel, means providing an axis of rotation for said support, and spaced from the grinding surface whereby angular motion of'the support causes a cylindrical surface to be ground, about said axis of rotation, and means for adjusting the position of said axis of rotation, said support comprising a split hub, and a tube axially movable through said hub, whereby said support may be adjusted along said axis of rotation.

5. In a grinding apparatus, a rotary cutting wheel having a fixed axis, said wheel forming a grinding surface, an angularly movable support for an object to be ground by the wheel, means providing an axis of rotation for said support and spaced from the grinding surface, whereby angular motion of the support causes a cylindrical surface to be ground about said axis of rotation, means for adjusting the position of said axis of rotation with respect to the wheel axis, an arm providing a gauging surface for said cylindrical surface, a bar upon which said arm is slidably mounted, said bar extending normally to said axis of rotation, and means whereby said arm is rotatable about the axis of said bar optionally to so position said gauging surface that it is parallel to said axis of rotation and has a normal intersecting the axis of rotation.

6. In a grinding apparatus, a rotary cutting wheel forming a vertically extending grinding surface, a frame for supporting said wheel, an angularly movable support for the work to be ground by the wheel, a support member providing an axis of rotation for said work support, and spaced from the grinding surface, whereby angular motion of the support causes a cylindrical surface to be ground about said axis, a bar for supporting said member and extending in a generally horizontal direction and being offset from the axis of the grinding wheel, said bar being slidably supported by a socket in the frame, means to prevent rotation of said bar in the socket, and means to move said bar axially to adjust the distance between said axis of rotation and the grinding surface.

7. In a grinding apparatus, a rotary cutting roll having a vertically extending axis, a fram for supporting the roll, an angularly movable support for the work to be ground, a support member providing an axis of rotation for the work support, said axes being parallel and spaced so that the axis of rotation is spaced from the surface of said roll, whereby angular motion of the support causes a cylindrical surface to be ground about said axis of revolution, a bar for supporting said member and extending horizontally, the bar being offset from the roll axis, said bar being slidably supported by a socket in the frame, means to prevent the bar rotating in the socket, means to move the bar axially to adjust the distance between said axes, and means to move the work support radially with respect to said axis of rotation to adjust the position of the work with respect to the grinding roll.

HJALMAR THOMASON. 

